a. Field of the Invention
The present invention relates generally to walking canes, and more particularly, to a walking cane having a tip assembly which is able to tilt and rotate relative to the shaft during use so as to reduce the possibility of a slip or fall.
b. Background Art
Most walking canes are provided with a rubber tip in an effort to provide stable engagement between the cane and a floor or other underlying support surface. In practice, however, it has been found that conventional rubber tips possess grave limitations which often result in severe injury to the user.
For example, with most rubber tips the shaft of the cane needs to be held in substantially vertical alignment, so that the contact patch on the bottom of the tip will be able to flatly engage the floor surface. Unfortunately, people frequently hold a cane at an outward angle from their bodies in an effort to steady themselves, so that the shaft extends at an angle to the floor rather than straight up and down. This causes the rubber tip to contact the floor at an angle, with only an edge of the tip engaging the floor surface. Consequently, when the person's weight bears on the cane at this angle, the tip tends to slide out, often causing the person to fall. Naturally, this problem is even more acute if the surface of the is slick or damp.
The problem of the tip slipping out becomes even more problematic when the person rotates the shaft of the cane with the natural motion of their hand/wrist as they walk or move about, since this twists the tip against the floor and tends to break it free from frictional engagement therewith.
Some prior attempts have been made at providing a cane tip which accommodates tilting of the shaft. Examples of these include devices which are shown in the following U.S. Pat. Nos.: 5,307,828 (Gardner et al.); 4,947,882 (Lavasseur); 4,881,564 (Fetterman); 2,419,105 (Allan); and 1,298,713 (Hipwood).
Most of these earlier devices have been too complex and cumbersome to be practical. For example, the Hipwood patent shows a device which provides a tilting and rotating action, but this uses a complex pneumatic mechanism and ball bearing arrangement.
Similarly, the Lavasseur reference shows a cumbersome assembly which employs a ball-and-socket mechanism with a large, domed, elastomeric ring which permits a degree of tilting motion; this device can also be tilted up by stepping on the edge of the base assembly when the cane is lying on the ground (see FIG. 4), but this requires the person to lift their foot a significant distance above the floor and requires a great deal of dexterity.
The Gardner patent shows another complex arrangement, which in this case uses a central plug which is mounted to the cane shaft and connected to a large rectangular pad by a rubber cord. In addition to being cumbersome, the range of motion which this device permits is limited by the elasticity of the rubber cord.
The Fetterman device employs an internal structure in which a soft, cushioning material deforms to accommodate irregularities in the surface or changes in angular orientation. Apart from the complexity and expense which are inherent in this design, deformation of the walls and base of the tip make it difficult for this device to maintain a flat contact surface with the floor under heavy loading. Moreover, the amount of tilting which is permitted by the device depends on the flexibility of the material, and the elastomeric loading of the material at high angular displacements tends to interfere with its ability to maintain stable engagement with the floor.
The Allan device, in turn, has a domed "hat member" which fits within the base of a cane tip having a more or less conventional shape, with a a second washer member on the end of the wooden shaft which rests atop the domed member to provide a rocking action. The upper washer has a downwardly-projecting saw tooth edge, so that this can be removed from the rubber tip and used on icy surfaces. Although this design has the advantage of simplicity, the rubber tip is still friction-mounted on the end of the shaft in essentially the same way as conventional tips, which prevents the shaft of the cane from twisting independently of the tip. Furthermore, like virtually all of the other devices described above, the resistance of the elastomeric member increases steadily with increasing angular displacement of the cane shaft, so that at greater angles the increased elastomeric loading tends to force the tip back towards alignment with the shaft and away from the horizontal plane of the floor. This creates a dangerous situation, since a momentary interruption of the downward pressure on the cane or a slippery surface may allow the tip to spring back towards alignment with the shaft, causing a loss of grip with the floor.
Another problem with existing types of canes is that these are often difficult for the user to pick up in the event that they are accidentally dropped. Since most cane users have impaired physical motions, they frequently lack the physical dexterity to bend over and reach the handle of a cane which is lying on the ground or floor. As was noted above, the device disclosed in the Lavasseur patent does little to alleviate this situation, since it is difficult to use and does not raise the cane handle high enough for this to be reached without having to bend over.
Accordingly, there exists a need for an anti-slip cane tip which is capable of remaining in perpendicular engagement with a floor or other support surface while the shaft of the cane is tilted through a large range of angular displacement. Moreover, there is a need for such a tip which will permit the shaft of the cane to be rotated independently of the tip, so that the user can twist the cane without fear of the tip losing its grip against the floor. Still further, there is a need for such a tip which will accommodate significant angular displacement of the shaft without causing increasing elastic loading of a resilient member which would tend to force the tip away from the plane of the floor. Still further, there is a need for such a tip which is simple and inexpensive in construction, and which employs a conventionally-shaped external rubber tip member so that this can be replaced easily and at minimal cost. Still further, there is a need for a cane having such a tip which can be picked up without the user having to bend over, in the event that the cane is accidentally dropped on the floor or other horizontal surface.